﻿namespace MsgBox.View.Modern.Windows.Converters
{
  using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Text;
  using System.Windows.Data;
  using System.Globalization;
  using System.Windows;

  /// <summary>
  /// Converts a null value to Visibility.Visible and any other value to Visibility.Collapsed
  /// </summary>
  public class NullToVisibilityConverter : IValueConverter
  {
    /// <summary>
    /// Converts a value.
    /// </summary>
    /// <param name="value">The value produced by the binding source.</param>
    /// <param name="targetType">The type of the binding target property.</param>
    /// <param name="parameter">The converter parameter to use.</param>
    /// <param name="culture">The culture to use in the converter.</param>
    /// <returns>
    /// A converted value. If the method returns null, the valid null value is used.
    /// </returns>
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
      var flag = value == null;
      var inverse = (parameter as string) == "inverse";

      if (inverse)
      {
        return (flag ? Visibility.Collapsed : Visibility.Visible);
      }
      else
      {
        return (flag ? Visibility.Visible : Visibility.Collapsed);
      }
    }

    /// <summary>
    /// Converts a value.
    /// </summary>
    /// <param name="value">The value that is produced by the binding target.</param>
    /// <param name="targetType">The type to convert to.</param>
    /// <param name="parameter">The converter parameter to use.</param>
    /// <param name="culture">The culture to use in the converter.</param>
    /// <returns>
    /// A converted value. If the method returns null, the valid null value is used.
    /// </returns>
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
      throw new NotSupportedException();
    }
  }
}
